Molecular mechanisms of restenosis after percutaneous peripheral angioplasty and approach to endovascular therapy.

Atherosclerosis is the most common cause of peripheral arterial disease (PAD). Interventional procedures are the first treatments proposed for most PAD patients. Balloon angioplasty alone may offer good immediate results; however, has it been proposed that the addition of stents improves the procedural success of angioplasty and extends its application to more types of lesions. Isolated aortic lesions are relatively rare, and the indications for stent placement have not been established. Percutaneous transluminal recanalization of chronic iliac occlusions remains controversial. However, results of recent studies have been encouraging, with initial technical success rates greater than 90%, low complication rates, and good long-term results. About the use of stent in atherosclerotic lesions involving iliac arteries and upper region of femoral arteries, we think that it is feasible. Differently, for the lower region of the femoral artery and for the popliteal artery, the results on the use of stents are controversial. More difficult is the therapy of infrapopliteal arteries disease in which perhaps the best option is medical therapy. The Transatlantic Inter-Society Consensus Group summarized the results of femoropopliteal stenting as follows: in a comparison of 11 trials involving femoropopliteal artery stenting in 585 patients, the primary patency rate was 58% at 36 months. For percutaneous transluminal angioplasty, the patency rates were 51% at 36 months. Although the results are satisfactory in femoral lesions, especially in stenoses shorter than 10 cm, they are less favorable both in longer femoral lesions than in the popliteal artery, where the results were worst. Large clinical series after angioplasty of lower limb arteries have confirmed the clinical and economical impact of restenosis: its rate varies in a range between 30% and 50%. The restenosis after stent deployment is the result of neointima formation; therefore, the interest of investigators turned towards an agent to suppress neointimal growth and restenosis after stent deployment, as Sirolimus and/or Taxolo. The first multicenter, randomized study, evaluating the 6-month outcomes of drug-eluting stent implantation in long-segment obstructions of the superficial femoral artery, was SMART trial, published in 2002. This is the first trial to show that controlled drug release is also feasible using a self-expandable nitinol stent platform. The results at 6 months demonstrate inhibition of in-stent neointimal proliferation, reflecting a trend toward a reduction in late loss.